Suction cups, per se, have long been known principally as novelty devices for suspending articles of light weight upon nonporous surfaces such as window panes, glazed ceramic tiles, etc. More recently, improved suction cups made of relatively soft plastic materials such as polyvinyl chloride have been developed, with improved design features such as a sturdy mounting base on the reverse side of the cup having a through-hole parallel to the suction face to hold a shelf, shower caddy or other storage device. These suction cups have been found, surprisingly, capable of holding substantial weights.
The former novelty device, due to superior technology, may now be regarded as an engineering development in the area of load support devices. Despite the new technology in suction cup development, they are still only capable of engineering utility when mounted upon non-porous surfaces such as glass, glazed ceramic tile, etc. Even then, care is required when mounting the suction cups to obtain satisfactory load-carrying capability. It must be remembered that the force responsible for adhering the cup to a surface is atmospheric pressure. Hence, mounting on a porous wall is a problem since infiltration of air to the interface between cup and wall results in equalization of pressure between the suction face and the reverse face of the cup, and it then drops off the wall.
It is to be recognized that the utility of suction cup mounted devices would be increased considerably if mounting upon a porous wall surface became possible. The present invention is directed to the solution of this problem. It must be remembered that homes and commercial buildings are characterized in the main by porous wall surfaces such as plaster, wall board, wood, cinder block, concrete block, etc., to which suction cups do not adhere.